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16#define pr_fmt(fmt) "kexec_elf: " fmt
17
18#include <linux/elf.h>
19#include <linux/kexec.h>
20#include <linux/libfdt.h>
21#include <linux/module.h>
22#include <linux/of_fdt.h>
23#include <linux/slab.h>
24#include <linux/types.h>
25
26#define PURGATORY_STACK_SIZE (16 * 1024)
27
28#define elf_addr_to_cpu elf64_to_cpu
29
30#ifndef Elf_Rel
31#define Elf_Rel Elf64_Rel
32#endif
33
34struct elf_info {
35
36
37
38
39 const char *buffer;
40
41 const struct elfhdr *ehdr;
42 const struct elf_phdr *proghdrs;
43 struct elf_shdr *sechdrs;
44};
45
46static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
47{
48 return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
49}
50
51static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
52{
53 if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
54 value = le64_to_cpu(value);
55 else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
56 value = be64_to_cpu(value);
57
58 return value;
59}
60
61static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
62{
63 if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
64 value = le16_to_cpu(value);
65 else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
66 value = be16_to_cpu(value);
67
68 return value;
69}
70
71static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
72{
73 if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
74 value = le32_to_cpu(value);
75 else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
76 value = be32_to_cpu(value);
77
78 return value;
79}
80
81
82
83
84
85static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
86{
87 if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
88 pr_debug("Bad program header size.\n");
89 return false;
90 } else if (ehdr->e_shnum > 0 &&
91 ehdr->e_shentsize != sizeof(struct elf_shdr)) {
92 pr_debug("Bad section header size.\n");
93 return false;
94 } else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
95 ehdr->e_version != EV_CURRENT) {
96 pr_debug("Unknown ELF version.\n");
97 return false;
98 }
99
100 if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
101 size_t phdr_size;
102
103
104
105
106
107 phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
108
109
110 if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
111 pr_debug("Program headers at invalid location.\n");
112 return false;
113 } else if (ehdr->e_phoff + phdr_size > buf_len) {
114 pr_debug("Program headers truncated.\n");
115 return false;
116 }
117 }
118
119 if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
120 size_t shdr_size;
121
122
123
124
125
126 shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
127
128
129 if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
130 pr_debug("Section headers at invalid location.\n");
131 return false;
132 } else if (ehdr->e_shoff + shdr_size > buf_len) {
133 pr_debug("Section headers truncated.\n");
134 return false;
135 }
136 }
137
138 return true;
139}
140
141static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
142{
143 struct elfhdr *buf_ehdr;
144
145 if (len < sizeof(*buf_ehdr)) {
146 pr_debug("Buffer is too small to hold ELF header.\n");
147 return -ENOEXEC;
148 }
149
150 memset(ehdr, 0, sizeof(*ehdr));
151 memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
152 if (!elf_is_elf_file(ehdr)) {
153 pr_debug("No ELF header magic.\n");
154 return -ENOEXEC;
155 }
156
157 if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
158 pr_debug("Not a supported ELF class.\n");
159 return -ENOEXEC;
160 } else if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
161 ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
162 pr_debug("Not a supported ELF data format.\n");
163 return -ENOEXEC;
164 }
165
166 buf_ehdr = (struct elfhdr *) buf;
167 if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
168 pr_debug("Bad ELF header size.\n");
169 return -ENOEXEC;
170 }
171
172 ehdr->e_type = elf16_to_cpu(ehdr, buf_ehdr->e_type);
173 ehdr->e_machine = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
174 ehdr->e_version = elf32_to_cpu(ehdr, buf_ehdr->e_version);
175 ehdr->e_entry = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
176 ehdr->e_phoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
177 ehdr->e_shoff = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
178 ehdr->e_flags = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
179 ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
180 ehdr->e_phnum = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
181 ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
182 ehdr->e_shnum = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
183 ehdr->e_shstrndx = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
184
185 return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
186}
187
188
189
190
191
192static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
193{
194
195 if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
196 pr_debug("ELF segment location wraps around.\n");
197 return false;
198 } else if (phdr->p_offset + phdr->p_filesz > buf_len) {
199 pr_debug("ELF segment not in file.\n");
200 return false;
201 } else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
202 pr_debug("ELF segment address wraps around.\n");
203 return false;
204 }
205
206 return true;
207}
208
209static int elf_read_phdr(const char *buf, size_t len, struct elf_info *elf_info,
210 int idx)
211{
212
213 struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
214 const char *pbuf;
215 struct elf_phdr *buf_phdr;
216
217 pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
218 buf_phdr = (struct elf_phdr *) pbuf;
219
220 phdr->p_type = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
221 phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
222 phdr->p_paddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
223 phdr->p_vaddr = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
224 phdr->p_flags = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
225
226
227
228
229
230 phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
231 phdr->p_memsz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
232 phdr->p_align = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
233
234 return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
235}
236
237
238
239
240
241
242
243static int elf_read_phdrs(const char *buf, size_t len,
244 struct elf_info *elf_info)
245{
246 size_t phdr_size, i;
247 const struct elfhdr *ehdr = elf_info->ehdr;
248
249
250
251
252
253 phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
254
255 elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
256 if (!elf_info->proghdrs)
257 return -ENOMEM;
258
259 for (i = 0; i < ehdr->e_phnum; i++) {
260 int ret;
261
262 ret = elf_read_phdr(buf, len, elf_info, i);
263 if (ret) {
264 kfree(elf_info->proghdrs);
265 elf_info->proghdrs = NULL;
266 return ret;
267 }
268 }
269
270 return 0;
271}
272
273
274
275
276
277static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)
278{
279 bool size_ok;
280
281
282 if (shdr->sh_type == SHT_NULL)
283 return true;
284
285
286 switch (shdr->sh_type) {
287 case SHT_SYMTAB:
288 size_ok = shdr->sh_entsize == sizeof(Elf_Sym);
289 break;
290 case SHT_RELA:
291 size_ok = shdr->sh_entsize == sizeof(Elf_Rela);
292 break;
293 case SHT_DYNAMIC:
294 size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);
295 break;
296 case SHT_REL:
297 size_ok = shdr->sh_entsize == sizeof(Elf_Rel);
298 break;
299 case SHT_NOTE:
300 case SHT_PROGBITS:
301 case SHT_HASH:
302 case SHT_NOBITS:
303 default:
304
305
306
307
308
309
310 size_ok = true;
311 break;
312 }
313
314 if (!size_ok) {
315 pr_debug("ELF section with wrong entry size.\n");
316 return false;
317 } else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {
318 pr_debug("ELF section address wraps around.\n");
319 return false;
320 }
321
322 if (shdr->sh_type != SHT_NOBITS) {
323 if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {
324 pr_debug("ELF section location wraps around.\n");
325 return false;
326 } else if (shdr->sh_offset + shdr->sh_size > buf_len) {
327 pr_debug("ELF section not in file.\n");
328 return false;
329 }
330 }
331
332 return true;
333}
334
335static int elf_read_shdr(const char *buf, size_t len, struct elf_info *elf_info,
336 int idx)
337{
338 struct elf_shdr *shdr = &elf_info->sechdrs[idx];
339 const struct elfhdr *ehdr = elf_info->ehdr;
340 const char *sbuf;
341 struct elf_shdr *buf_shdr;
342
343 sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);
344 buf_shdr = (struct elf_shdr *) sbuf;
345
346 shdr->sh_name = elf32_to_cpu(ehdr, buf_shdr->sh_name);
347 shdr->sh_type = elf32_to_cpu(ehdr, buf_shdr->sh_type);
348 shdr->sh_addr = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);
349 shdr->sh_offset = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);
350 shdr->sh_link = elf32_to_cpu(ehdr, buf_shdr->sh_link);
351 shdr->sh_info = elf32_to_cpu(ehdr, buf_shdr->sh_info);
352
353
354
355
356
357 shdr->sh_flags = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);
358 shdr->sh_size = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);
359 shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);
360 shdr->sh_entsize = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);
361
362 return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;
363}
364
365
366
367
368
369
370
371static int elf_read_shdrs(const char *buf, size_t len,
372 struct elf_info *elf_info)
373{
374 size_t shdr_size, i;
375
376
377
378
379
380 shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;
381
382 elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);
383 if (!elf_info->sechdrs)
384 return -ENOMEM;
385
386 for (i = 0; i < elf_info->ehdr->e_shnum; i++) {
387 int ret;
388
389 ret = elf_read_shdr(buf, len, elf_info, i);
390 if (ret) {
391 kfree(elf_info->sechdrs);
392 elf_info->sechdrs = NULL;
393 return ret;
394 }
395 }
396
397 return 0;
398}
399
400
401
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404
405
406
407
408
409
410
411
412
413
414int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
415 struct elf_info *elf_info)
416{
417 int ret;
418
419 ret = elf_read_ehdr(buf, len, ehdr);
420 if (ret)
421 return ret;
422
423 elf_info->buffer = buf;
424 elf_info->ehdr = ehdr;
425 if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
426 ret = elf_read_phdrs(buf, len, elf_info);
427 if (ret)
428 return ret;
429 }
430 if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
431 ret = elf_read_shdrs(buf, len, elf_info);
432 if (ret) {
433 kfree(elf_info->proghdrs);
434 return ret;
435 }
436 }
437
438 return 0;
439}
440
441
442
443
444void elf_free_info(struct elf_info *elf_info)
445{
446 kfree(elf_info->proghdrs);
447 kfree(elf_info->sechdrs);
448 memset(elf_info, 0, sizeof(*elf_info));
449}
450
451
452
453static int build_elf_exec_info(const char *buf, size_t len, struct elfhdr *ehdr,
454 struct elf_info *elf_info)
455{
456 int i;
457 int ret;
458
459 ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
460 if (ret)
461 return ret;
462
463
464 if (ehdr->e_type != ET_EXEC && ehdr->e_type != ET_DYN) {
465 pr_err("Not an ELF executable.\n");
466 goto error;
467 } else if (!elf_info->proghdrs) {
468 pr_err("No ELF program header.\n");
469 goto error;
470 }
471
472 for (i = 0; i < ehdr->e_phnum; i++) {
473
474
475
476
477
478 if (elf_info->proghdrs[i].p_type == PT_INTERP) {
479 pr_err("Requires an ELF interpreter.\n");
480 goto error;
481 }
482 }
483
484 return 0;
485error:
486 elf_free_info(elf_info);
487 return -ENOEXEC;
488}
489
490static int elf64_probe(const char *buf, unsigned long len)
491{
492 struct elfhdr ehdr;
493 struct elf_info elf_info;
494 int ret;
495
496 ret = build_elf_exec_info(buf, len, &ehdr, &elf_info);
497 if (ret)
498 return ret;
499
500 elf_free_info(&elf_info);
501
502 return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
503}
504
505
506
507
508
509
510
511
512
513static int elf_exec_load(struct kimage *image, struct elfhdr *ehdr,
514 struct elf_info *elf_info,
515 unsigned long *lowest_load_addr)
516{
517 unsigned long base = 0, lowest_addr = UINT_MAX;
518 int ret;
519 size_t i;
520 struct kexec_buf kbuf = { .image = image, .buf_max = ppc64_rma_size,
521 .top_down = false };
522
523
524 for (i = 0; i < ehdr->e_phnum; i++) {
525 unsigned long load_addr;
526 size_t size;
527 const struct elf_phdr *phdr;
528
529 phdr = &elf_info->proghdrs[i];
530 if (phdr->p_type != PT_LOAD)
531 continue;
532
533 size = phdr->p_filesz;
534 if (size > phdr->p_memsz)
535 size = phdr->p_memsz;
536
537 kbuf.buffer = (void *) elf_info->buffer + phdr->p_offset;
538 kbuf.bufsz = size;
539 kbuf.memsz = phdr->p_memsz;
540 kbuf.buf_align = phdr->p_align;
541 kbuf.buf_min = phdr->p_paddr + base;
542 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
543 ret = kexec_add_buffer(&kbuf);
544 if (ret)
545 goto out;
546 load_addr = kbuf.mem;
547
548 if (load_addr < lowest_addr)
549 lowest_addr = load_addr;
550 }
551
552
553 ehdr->e_entry += base;
554
555 *lowest_load_addr = lowest_addr;
556 ret = 0;
557 out:
558 return ret;
559}
560
561static void *elf64_load(struct kimage *image, char *kernel_buf,
562 unsigned long kernel_len, char *initrd,
563 unsigned long initrd_len, char *cmdline,
564 unsigned long cmdline_len)
565{
566 int ret;
567 unsigned int fdt_size;
568 unsigned long kernel_load_addr;
569 unsigned long initrd_load_addr = 0, fdt_load_addr;
570 void *fdt;
571 const void *slave_code;
572 struct elfhdr ehdr;
573 struct elf_info elf_info;
574 struct kexec_buf kbuf = { .image = image, .buf_min = 0,
575 .buf_max = ppc64_rma_size };
576 struct kexec_buf pbuf = { .image = image, .buf_min = 0,
577 .buf_max = ppc64_rma_size, .top_down = true,
578 .mem = KEXEC_BUF_MEM_UNKNOWN };
579
580 ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
581 if (ret)
582 goto out;
583
584 ret = elf_exec_load(image, &ehdr, &elf_info, &kernel_load_addr);
585 if (ret)
586 goto out;
587
588 pr_debug("Loaded the kernel at 0x%lx\n", kernel_load_addr);
589
590 ret = kexec_load_purgatory(image, &pbuf);
591 if (ret) {
592 pr_err("Loading purgatory failed.\n");
593 goto out;
594 }
595
596 pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
597
598 if (initrd != NULL) {
599 kbuf.buffer = initrd;
600 kbuf.bufsz = kbuf.memsz = initrd_len;
601 kbuf.buf_align = PAGE_SIZE;
602 kbuf.top_down = false;
603 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
604 ret = kexec_add_buffer(&kbuf);
605 if (ret)
606 goto out;
607 initrd_load_addr = kbuf.mem;
608
609 pr_debug("Loaded initrd at 0x%lx\n", initrd_load_addr);
610 }
611
612 fdt_size = fdt_totalsize(initial_boot_params) * 2;
613 fdt = kmalloc(fdt_size, GFP_KERNEL);
614 if (!fdt) {
615 pr_err("Not enough memory for the device tree.\n");
616 ret = -ENOMEM;
617 goto out;
618 }
619 ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
620 if (ret < 0) {
621 pr_err("Error setting up the new device tree.\n");
622 ret = -EINVAL;
623 goto out;
624 }
625
626 ret = setup_new_fdt(image, fdt, initrd_load_addr, initrd_len, cmdline);
627 if (ret)
628 goto out;
629
630 fdt_pack(fdt);
631
632 kbuf.buffer = fdt;
633 kbuf.bufsz = kbuf.memsz = fdt_size;
634 kbuf.buf_align = PAGE_SIZE;
635 kbuf.top_down = true;
636 kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
637 ret = kexec_add_buffer(&kbuf);
638 if (ret)
639 goto out;
640 fdt_load_addr = kbuf.mem;
641
642 pr_debug("Loaded device tree at 0x%lx\n", fdt_load_addr);
643
644 slave_code = elf_info.buffer + elf_info.proghdrs[0].p_offset;
645 ret = setup_purgatory(image, slave_code, fdt, kernel_load_addr,
646 fdt_load_addr);
647 if (ret)
648 pr_err("Error setting up the purgatory.\n");
649
650out:
651 elf_free_info(&elf_info);
652
653
654 return ret ? ERR_PTR(ret) : fdt;
655}
656
657const struct kexec_file_ops kexec_elf64_ops = {
658 .probe = elf64_probe,
659 .load = elf64_load,
660};
661